186.3.] ;[95 [Lesley. 



at least fifty thousand square miles of the surface of the United 

 States, merely along the one belt of the Appalachian Mountains, be- 

 tween the great coal area and the Blue Ridge range. What has re- 

 moved these massifs ? The excavation of a hundred Lake Superiors 

 to the depth of two thousand feet would not present the same diffi- 

 culties. Either a cataclysmic subaerial deluge mighty enough to do 

 the work, or a series of such deluges following each other until the 

 work was done, or the atmospheric agencies at work on every square 

 inch of the whole area for almost an infinity of ages, — one or other of 

 these three must be the accepted force. Ice may come in for its share 

 of the byplay, at various and very early times (as Ramsay has made 

 probable in Shropshire) as well as in the last days of its glory, the 

 stamp of which we see left upon our outcrop surfaces; but to make it 

 the initial agency of such erosion is absurd. The power of ice could no 

 more have swept those symmetrical palaeozoic arches into the Atlan- 

 tic, than a child could have flown to Loretto with its church. But 

 whatever did accomplish that work, did it all ; established the gene- 

 ral register of heights; made every mountain a consistent part of the 

 harmonious whole; worked out all the Lower Silurian valleys pre- 

 cisely on one pattern ; excavated every Devonian lake from Harvey's 

 Pond to Lake Huron alike; and cut to the same contour the subcar- 

 boniferous cliffs along the whole line from the icy Delaware to the 

 sunny Alabama. 



Of the seven or more chief points of speculation cited above, that 

 of the split anticlinal is of course the most important. The admira- 

 ble illustrations of the Austrian survey, which Haidinger and his 

 noble coadjutors have been giving us for several years, repeat with 

 variations all the curiosities of our Appalachian anticlinal structure, 

 which were prepared for publication twenty years ago by the State 

 Survey of Pennsylvania. But being chiefly sections of younger rocks 

 than ours, the Austrian diagrams exhibit a more disturbed surface, 

 so far as regards faults and slips, snapped anticlinals, upshoved syn- 

 clinals, lapped folds, insertions or knife-edge intrusions of fragmen- 

 tary strata, &c., while the main features are all the same. This may 

 hereafter be adduced by some one as an evidence of the necessity of 

 assigning quite a modern date to our contortions ; inasmuch as dis- 

 turbances, relatively as old (that is, occurring when the palaeozoic rocks 

 had as yet obtained no greater consistency and compactness than the 

 newer secondaries or tertiaries of the Alps) ought to have dealt as 

 hardly with those, as the Austrian subterranean forces have dealt 

 with these. But that would be a hazardous conclusion ; for the na- 



